The Lost Fraggles introduce themselves via their theme song.
The Lost Fraggles are a group of Fraggles that live deep underneath the better-known part of Fraggle Rock - Lost Fraggle Rock. Gobo discovers their dwelling at the very end of the Fraggle Rock: Back to the Rock episode "Fraggle Up" and he and his friends (Wembley, Red, Mokey, Boober, Lanford, and Cotterpin) learn more about them in the following episode.
While most of the Fraggles are very similar to the various background Fraggles (though all wear handmade muted outfits), most of the Fraggle five is surprised to see that they each have a counterpart that is similar in both look and personality. Mokey is the only one who doesn't meet her counterpart during their visit... but only because "Slowpokey" arrives after the others leave.
Just as Wembley is named after Wembley Stadium in London, Wrigley is named after Wrigley Field in Chicago.
